DVDs are generalized as optical discs on which various information is recorded, such as content information, e.g. the video information, the audio information, and the sub picture information, and the reproduction control information. According to the DVD standard, the video information (e.g. video data), the audio information (e.g. audio data), and the sub picture information (e.g. sub picture data) are individually packetized with the reproduction control information (e.g. navigation data) and are multiplexed and recorded on a disc in the “program stream” format of the MPEG 2 (Moving Picture Experts Group phase 2) standard, which is a highly efficient encoding technique. In the video information among them, there is only one stream of data compressed according to the MPEG video format (ISO 13818-2) within one program stream. On the other hand, the audio information is recorded in a plurality of methods (namely, linear PCM, AC-3, MPEG audio, and the like). The audio information can exist up to 8 streams within one program stream. The sub picture information is defined with a bit map and is compressed and recorded in a run-length method. The sub picture information can exist up to 32 streams within one program stream. In the case of the DVD, as described above, a plurality of streams of the chooseable or selectable audio information (e.g. streams of a stereo sound, a surrounding sound, an original English sound, a dubbed Japanese sound, and the like) and a plurality of streams of the chooseable or selectable sub picture information (e.g. streams of Japanese subtitle, English subtitle, and the like) are multiplexed and recorded by using the program stream format, for one stream of the video information in one movie or film, for example.
On the other hand, the “transport stream” format of the MPEG 2 standard has been recently standardized, and this is appropriate for data transmission. According to this transport stream format, a plurality of “elementary streams” are transmitted at the same time. For example, a plurality of shows or programs, such as many TV channels of satellite digital broadcasting, are time-division-multiplexed to one satellite wave and are transmitted at the same time. Namely, in the transport stream format, it is possible to time-division-multiplex the elementary streams of a plurality of main pictures or video, each of which has a large data amount, and transmit them at the same time. For example, it is possible to transmit at the same time a plurality of movies recorded on a plurality of DVDs.